Due to riot shield being a donation tool/weapon I don't think that you can get it on riot control.
Flare gun has too much AOE and would cause multiple problems in dblock like lighting props on fire causing lag.
Flash bangs would be kinda terrible for riots as it blinds your team mates also more than 70% of the time
Stun sticks would be cool but would sorta take away from SCP 912's whole idea.
Tear gas is a no as it's only really used for mass riots and terrible occassions with mag lockdown being the worst case scenario.
I think Riot Control is sorta in a good place right now only really needing minor buffs like a secondary change. The double barrel is really good for controlling riots.